The Vast Explorer
To map the Whydah's debris field, Clifford towed a magnetometer behind his ship, the Vast Explorer. After finding the artifacts, divers made a grid of the excavation area in one-inch squares.
Photo by Brian Skerry © Image Collection
The first step to locating and recovering artifacts from the Whydah involved determining the size of the debris field and sectioning off sections to investigate. This was done in much the same way that archaeologists examine dig sites on land. The entire area is marked off to denote the space in which artifact "hits" were indicated when they swept the area with a proton precision magnetometer.
After locating the possible site of the shipwreck, the Expedition Whydah crew lowers 3 or more anchors to secure their boat in place over the wreck site. Next, they attach a device called a "mailbox" over the propeller of the boat and angle it down so that the wash from the prop is directed towards the sea floor where artifacts are thought to be buried beneath the sand. It's not a simple matter of picking up exposed gold coins and cannons though. A lot of the cargo and items on board the Whydah when she sank became encapsulated in concretions; masses of sand, rock and clay that have bound to metal objects that have been exposed to seawater for long periods of time.
Concretion
When concretions are brought to the surface, they are immediately placed into a tank of freshwater.
Anywhere from 2 to 4 weeks later, they get moved to a different tank that is filled with a chemical solution.
Photo by Matthew Prefontaine © Arts and Exhibitions International
When concretions are brought to the surface, they are immediately placed into a tank of freshwater. Anywhere from 2 to 4 weeks later, they get moved to a different tank that is filled with a chemical solution. Once the concretions have soaked in the solution, a low-voltage electrical current is then applied to the tank in a process called "electrolytic reduction". Next, any salts adhered to the artifacts are rinsed off, which aids in the removal of stones and debris from the artifacts. Afterward, any remaining concretion is removed carefully by hand using brushes and picks. The artifacts are now washed and dried. Finally, a protective coating, or sealant, is applied to the artifacts.
~~ Concretions ~~
